- adjust some tests and such to work better with a mysql 5.5 install

  - Added mysql_length parameter to Index construct,
    specifies "length" for indexes.  [ticket:2293]

2 files changed, 52 insertions, 0 deletions

diff --git a/lib/sqlalchemy/dialects/mysql/base.py b/lib/sqlalchemy/dialects/mysql/base.py
index 80067f9dc..1a30e15fd 100644
--- a/lib/sqlalchemy/dialects/mysql/base.py
+++ b/lib/sqlalchemy/dialects/mysql/base.py
@@ -197,6 +197,32 @@ within an application, overrides the compilation of the
 fully rendering CAST; else the internal element of the
 construct is rendered directly.
 
+
+.. _mysql_indexes:
+
+MySQL Specific Index Options
+----------------------------
+
+MySQL-specific extensions to the :class:`.Index` construct are available.
+
+Index Length
+~~~~~~~~~~~~~
+
+MySQL provides an option to create index entries with a certain length, where
+"length" refers to the number of characters or bytes in each value which will
+become part of the index. SQLAlchemy provides this feature via the
+``mysql_length`` parameter::
+
+    Index('my_index', my_table.c.data, mysql_length=10)
+
+Prefix lengths are given in characters for nonbinary string types and in bytes
+for binary string types. The value passed to the keyword argument will be
+simply passed through to the underlying CREATE INDEX command, so it *must* be
+an integer. MySQL only allows a length for an index if it is for a CHAR,
+VARCHAR, TEXT, BINARY, VARBINARY and BLOB.
+
+More information can be found at:
+http://dev.mysql.com/doc/refman/5.0/en/create-index.html
 """
 
 import datetime, inspect, re, sys
@@ -1395,6 +1421,30 @@ class MySQLDDLCompiler(compiler.DDLCompiler):
             table_opts.append(joiner.join((opt, arg)))
         return ' '.join(table_opts)
 
+    def visit_create_index(self, create):
+        index = create.element
+        preparer = self.preparer
+        text = "CREATE "
+        if index.unique:
+            text += "UNIQUE "
+        text += "INDEX %s ON %s " \
+                    % (preparer.quote(self._index_identifier(index.name), 
+                        index.quote),preparer.format_table(index.table))
+        if 'mysql_length' in index.kwargs:
+            length = index.kwargs['mysql_length']
+        else:
+            length = None
+        if length is not None:
+            text+= "(%s(%d))" \
+                    % (', '.join(preparer.quote(c.name, c.quote)
+                                 for c in index.columns), length)
+        else:
+            text+= "(%s)" \
+                    % (', '.join(preparer.quote(c.name, c.quote)
+                                 for c in index.columns))
+        return text
+
+
     def visit_drop_index(self, drop):
         index = drop.element
 
diff --git a/lib/sqlalchemy/schema.py b/lib/sqlalchemy/schema.py
index 99c8acbfe..3d00b3197 100644
--- a/lib/sqlalchemy/schema.py
+++ b/lib/sqlalchemy/schema.py
@@ -2086,6 +2086,8 @@ class Index(ColumnCollectionMixin, SchemaItem):
     :ref:`schema_indexes` - General information on :class:`.Index`.
 
     :ref:`postgresql_indexes` - PostgreSQL-specific options available for the :class:`.Index` construct.
+
+    :ref:`mysql_indexes` - MySQL-specific options available for the :class:`.Index` construct.
     """
 
     __visit_name__ = 'index'